Re: [gentoo-user] mmx use flag on Pentium 4

["Walter Dnes" <waltdnes@waltdnes.org>]

On Sat, Sep 24, 2005 at 11:10:35PM +0100, Jonathan Wright wrote

> however since that version -mcpu has been depreciated in favor for -mtune.

  I use -march, so that point is moot.

> As for the mmx information, that's valid across all gcc versions. If
> you specify -march=pentium4 and -mcpu=pentium4 as part of your
> CFLAGS, -mmmx and -msse, etc., will be implied by the compiler,
> and any programs built to take advantage of the extensions will be
> able to do so.

  The docs for 3.4.X are a lot more detailed than 3.3.X docs.  3.3.6
docs say that -march implies -mcpu but don't say in so many words that
certain values of -march imply -sse, etc.

  While we're talking about compilers and sparse documentation, I've got
an AMD64 K8.  The docs for an AMD64-bit install scared me off to 32-bit
land.  Later I found out that the 64-bit install docs are out-of-date
and the problems they mention seem to have been solved.  However, since
I have things humming along, I don't really want to tear my install down
and rebuild from scratch.  One question... I'm running
> CFLAGS="-O2 -pipe -fomit-frame-pointer -march=athlon -m3dnow -mmmx -msse -msse2 -mfpmath=sse"

  Is there a way to figure out if I can use a higher version of Athlon
in my CFLAGS line in 32-bit mode?

-- 
Walter Dnes <waltdnes@waltdnes.org>
My musings on technology and security at http://tech_sec.blog.ca
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